The epidemiology of irritable bowel syndrome (IBS) in Europe and North America was analyzed from published material. The percentage of the population of Western civilisation with IBS symptoms is between 10 and 15% in most studies. The proportion of a Western population visiting a doctor for IBS symptoms is around 5%. The prevalence of IBS and the proportion of consulters do not seem to depend on age in an adult population. The female-to-male ratio of IBS in the population is close to 2. It is higher in IBS consulters in primary care and may be as high as 3 or 4 in tertiary referral centers. At least in patients from these centers, the number of physician visits and colonoscopies is considerable. Most of the consulters get a drug prescription.